Printing apparatus and method to pick up paper

ABSTRACT

A printing apparatus and a method to pick up paper using the printing apparatus. The printing apparatus includes a main body; a signal supply section to supply a signal indicative of a type of a paper to be fed from a paper feeding section provided in the main body; at least one friction member provided to form an angle within a predetermined range in relation to the leading edge of a paper picked up from the paper feeding section so that predetermined frictional force is applied to the leading edge of the paper, the friction member being installed to changeable structure within the range; at least one elastic member to elastically bias the friction member in a first direction; a cam unit movably installed to the main body, the cam unit forcibly moving the friction member in a second direction opposite to the first direction to change the structure of the friction member while the cam unit is being moved by driving force; a driving force supply unit movably installed in the main body, the driving force supply unit to supply driving force to the cam unit at the time of being moved; and a control section to control the driving of the driving force supply unit based on the signal in relation to the type of the paper supplied from the signal supply section.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2003-36125, filed Jun. 4, 2003, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a printing apparatus, and inparticular, to a printing apparatus having a flexible structure of afriction member to classify a plurality of papers according torespective type of the plurality of papers.

[0004] 2. Description of the Related Art

[0005] Generally, a printing apparatus such as a laser printer and anink-jet printer comprise a paper-feeding device to individually feedeach paper to a printing stage of the printing apparatus.

[0006] In general, such a paper feeding device comprises a papercartridge section on which a plurality of papers are loaded, at leastone pick-up roller to feed the plurality of papers loaded on the papercartridge section in one direction, and at least one friction memberprovided at a predetermined angle in relation to the paper transferdirection so as to individually classify the plurality of papers fed andforwarded by the pick-up roller.

[0007] The friction member is provided at a predetermined angle inrelation to a bottom surface of the paper cartridge, i.e., to ahorizontal surface on which the papers are loaded. When the leading edgeof a paper picked up by the pick-up roller comes into contact with thefriction member, a paper is separated from the plurality of papers bythe frictional force, and then moved to a printing section.

[0008] However, because the installation angle of the friction member istypically fixed and unchangeable, it is difficult to dynamicallyaccommodate various types of print papers. Specifically, when the loadedpaper is thick and stiff, or for example, glossy, sometimes the papermay not be picked up due to the stiffness of the paper because theresistance between the leading edge of the paper to be picked up and thefriction member is too large.

[0009] Further, in a case where the paper is relatively thin as comparedto a glossy paper, two or more sheets of paper may be concurrentlypicked up.

SUMMARY OF THE INVENTION

[0010] Accordingly, the present invention is provided to solve theabove-mentioned and/or other problems of the related art, and an aspectof the present invention provides a printing apparatus having animproved flexible structure to accommodate various types of papers bydynamically changing a structure of a friction member in accordance withthe types of papers fed.

[0011] In order to achieve the above and/or other aspects of the presentinvention, a printing apparatus is provided that comprises: a main body;a signal supply section to supply a signal indicative of types of paperfed from a paper feeding section provided to the main body; at least onefriction member provided at an angle within a predetermined range inrelation to the leading edge of a paper picked up from the paper feedingsection, wherein the at least one friction member has an adjustablestructure that is capable of changing within the predetermined range; atleast one elastic member to elastically bias the at least one frictionmember in a first direction; a cam unit movably installed to the mainbody, wherein the cam unit forcibly moves the at least one frictionmember in a second direction opposite to the first direction to changethe structure of the at least one friction member while the cam unit isbeing moved by a driving force; a driving force supply unit movablyinstalled to the main body to supply a driving force to the cam unit atthe time of being moved; and a control section to control the driving ofthe driving force supply unit based on the signal in relation to thetype of the paper supplied from the signal supply section.

[0012] Additional aspects and advantages of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0013] According to an aspect of the present invention, the cam unitcomprises: a camshaft rotatably installed to the main body, having atleast one projection contacted with the rear surface of the at least onefriction member; and a link arm pivotably installed to the main bodythat connectively moves the camshaft to rotate the camshaft while beingpivoted, the link arm being selectively pivoted by the driving forcesupply unit.

[0014] In addition, according to an aspect of the present invention, thedriving force supply unit comprises: a carriage to receive an inkcartridge, installed to the main body so as to reciprocate; and acontact member connected to the carriage, wherein the contact membermakes contact with the cam unit to forcibly move the cam unit to apredetermined area when the carriage moves.

[0015] According to another aspect of the present invention, thecarriage is movable between a printing area to print an image on a paperand a home position spaced from the printing area, and the carriageinterferes with the cam unit when the carriage moves from the printingarea to the home position.

[0016] Furthermore, according to an aspect of the present invention, twoor more friction members may be provided having a predetermined intervaltherebetween, and the camshaft may comprise two or more cam projectionsto correspond to the two or more friction members, respectively, and alink pin offset provided at a rotational center of the camshaft.

[0017] According to an aspect of the present invention, the link armcomprises: a slot at one end and a guide part at the other end, and thelink pin is engaged in the slot and the guide part has a contactsurface, which is slantly formed in relation to the direction of therotational axis of the link arm and contacts with the driving forcesupply unit.

[0018] According to another aspect of the present invention, the signalsupply section comprises a paper detection sensor to detect the type ofpaper loaded in the paper feeding section.

[0019] The signal supply section may also comprise memory to storeinformation in relation to the type of paper inputted through a printdriver in accordance with a user's choice.

[0020] Further, paper loaded in the paper feeding section may include afirst type of paper having a thickness within a predetermined range, anda second type of paper thicker than the first type of paper. In such acase, when the first type of paper is loaded in the paper feedingsection, the control section drives the driving force supply unit sothat the friction member is moved in the second direction to change thestructure of the friction member.

[0021] According to an aspect of the invention, the friction memberforms a larger angle in relation to the leading edge of a paper to bepicked up when the friction member has been forcibly moved than when thefriction member has been elastically biased.

[0022] According to another aspect of the present invention, a method ofpicking up paper in a printing apparatus is provided. Accordingly, theprinting apparatus comprises: a main body; at least one friction member,installed to the main body, having a flexible structure to form an anglein relation to a leading edge of a paper picked up from a paper feedingunit and elastically biased in a first direction; a cam unit movablyinstalled to the main body to forcibly move the at least one frictionmember in a second direction opposite to the first direction while thecam unit is being moved by driving force; and a driving force supplyunit movably installed to the main body to supply a driving force to thecam unit at the time the cam unit is being moved. The method comprises:supplying a signal indicative of a type of paper to be picked up;classifying the paper to a first type having a thickness within apredetermined range or a second type thicker than the first type basedon the signal; supplying driving force to the cam unit upon classifyingthe paper as the first type; moving the friction member to the seconddirection by driving the cam unit; and picking up the paper from thepaper feeding section when the friction member has been moved in thesecond direction.

[0023] According to another aspect of the present invention theoperation of supplying the signal comprises: supplying a detectionsignal from a detection sensor that detects the type of paper loaded inthe paper feeding section provided to the main body.

[0024] According to another aspect of the present invention, theoperation of supplying the signal comprises: supplying a signal frommemory having stored information in relation to types of papers inputtedthrough a print driver by a user.

[0025] Further, the printing apparatus may further comprise: a carriageinstalled to the main body to reciprocate between a printing area and ahome position, and a contact member connected to the carriage toconnectively move the cam unit when the carriage is moved. Accordingly,when the driving force is supplied and the carriage is positioned at theprinting area, the carriage positioned at the printing area is moved tothe home position, and the contact member comes in contact with the camunit when the carriage is moved to the home position.

[0026] According to another aspect of the invention, the printingapparatus further comprises: a link arm pivotably installed to the mainbody, and the cam unit having a camshaft provided with at least one camprojection. Accordingly, when the friction member is moved in the seconddirection, the link arm comes in contact with the driving force supplyunit and receives driving force, thereby, being pivoted, the camshaftlinked to the link arm is connectively rotated, and the cam projectionmakes contact with and compresses the rear surface of the frictionmember in the second direction while the cam projection is being rotatedalong with the camshaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and/or other aspects and advantages of the inventionwill become more apparent, and more readily appreciated from thefollowing description of the preferred embodiments, taken in conjunctionwith accompanying drawings of which:

[0028]FIG. 1 is a schematic perspective view to show a printingapparatus according to an aspect of the present invention;

[0029]FIG. 2 is a block diagram to illustrate the printing apparatusaccording to an aspect of the present invention;

[0030]FIG. 3 is a cross-sectional view of a main part of the printingapparatus shown in FIG. 1;

[0031]FIG. 4 is a perspective view of the main part of the printingapparatus shown in FIG. 1;

[0032]FIG. 5 is a perspective view of a main part of the printingapparatus shown in FIG. 4;

[0033]FIG. 6 is a flowchart to illustrate a method to pick up a paper inthe printing apparatus according to an aspect of the present invention;

[0034]FIG. 7 is a side elevational view to show the carriage positionedin the printing area; and

[0035]FIG. 8 is a side elevational view to show the carriage moved tothe home position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Reference will now be made in detail to the embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout.

[0037] As shown in FIGS. 1 and 2, the printing apparatus according to anaspect of the present invention comprises: a main body 10; a paperfeeding section 20 provided to the lower part of the main body 10; apick-up unit 30 to pick up paper loaded to the paper feeding section 20;a signal supply section 40 to supply a signal indicative of a type ofthe paper loaded to the paper feeding section 20; at least one frictionmember 50 provided to a side of the paper feeding section 20; at leastone elastic member 60 to elastically bias the at least one frictionmember 50 in a first direction; a cam unit 70 to move the at least onefriction member 50 in a second direction opposite to the first directionwhile being moved by a driving force; a driving force supply unit 80 tosupply the driving force to the cam unit 70; and a control section 90 tocontrol the operation of the driving force supply unit 80.

[0038] As shown in FIG. 1, the main body 10 comprises: a base 11 and amain frame 13 installed to a top portion of the base 11. The top surfaceof the base 11 is provided with the paper feeding section 20 to whichsheets of paper to be picked are loaded.

[0039] The main frame 13 supports the pick-up unit 30, which picks upthe paper provided to the paper feeding section 20, and the main frame13 is provided with a transfer roller 14 to transfer the paper, a guidemember, etc. In addition, the main frame 13 is also provided with ashaft 16 to support a carriage 15, wherein the carriage 15 reciprocateswhile carrying an ink cartridge. Further, a timing belt (not shown) anda driving motor (not shown) are also provided for reciprocating thecarriage 15.

[0040] A plurality of papers are loaded to the paper feeding section 20and are fed individually by the pick-up unit 30. The plurality of papersfed to the paper feeding section 20 are transferred below the carriage15 through the friction member 50, the transfer roller 14, etc.

[0041] The pick-up unit 30, having a construction typically and widelyemployed in printing apparatus comprises a pick-up roller 31, and aroller shaft 33. The roller shaft 33 is connected to a pivot member thatmoves up and down. The pick-up roller 31 picks up paper while beingrotated by the driving motor, which is not shown.

[0042] Further, the signal supply section 40 supplies a signalindicative of a type of paper and serves to provide informationconcerning a type of paper loaded to the paper feeding section 20, forexample, information regarding thickness of the paper. The signal supplysection 40 comprises: a sensor 41 to directly detect the type of paperloaded to the paper feeding section 20. The sensor 41 may be alight-receiving/emitting sensor or a resistance sensor, which detectsthe thickness of a paper by measuring a resistance value of the paper.

[0043] The signal supply section 40 may be provided with a memory 43 inwhich data values regarding types of paper inputted by a user through aprinter driver are stored. Therefore, the control section 90 receives atleast one data signal regarding the type of paper to be picked up, whichis inputted to the memory 43, to determine the type of paper. In thiscase, the signals concerning the types of paper transmitted to thesignal section 40 may be classified into a signal of a first type ofpaper having a thickness within a predetermined range, and a signal of asecond type of paper thicker than the first type of paper.

[0044] The at least one friction member 50 is installed in such a waythat a predetermined frictional force is provided to the leading edge ofa paper to be picked. That is, the friction member 50 is installed toform an angle within a predetermined range in relation to the transferdirection of the picked-up paper, and to change the structure of thefriction member within the range. As shown in FIG. 3, the lower end ofthe friction member 50 is pivotably supported on the base of the mainbody by a pivot pin 51, and the upper end is connected to the elasticmember 60 and elastically biased to a first direction A. One end of theelastic member 60 is connected to the rear surface of the frictionmember 50, and the other end is connected to the base 11. In addition,the base 11 is provided with a projection rib 11 a, against which thefriction member 50 is abutted, so that the structure of the frictionmember 50 is fixed to move in the first direction A in one state. Inthis state, when a force is applied to the friction member 50 in thesecond direction B, the friction member 50 is further pivoted in thesecond direction B, thereby, allowing the structure of the frictionmember to change.

[0045] Accordingly, the angle formed between the friction member 50 andthe leading edge of the paper when the friction member 50 is moved inthe first direction A, as shown in FIG. 5, is larger than the angleformed when the friction member 50 is moved in the second direction B.Therefore, when the friction member 50 is moved in the first directionA, the frictional force between the friction member 50 and the leadingedge of the paper will decrease. Accordingly, the position of thefriction member 50 is adjusted to maintaining an angle appropriate topick up the second type of paper, which is thicker in comparison to thefirst type of paper.

[0046] According to an aspect of the present invention, at least twofriction members 50 are provided that are equi-spaced from each otherand the position of all the friction members 50 concurrently changes tohave uniform positions. The base 11 is formed with at least twoequi-spaced projection ribs 11 a, so that the projections 11 acorrespond to the friction members 50, respectively.

[0047] The cam unit 70 serves to push the friction members 50 to bemoved by a driving force in the second direction, so that the frictionmembers 50 change their position. As shown in FIGS. 4 and 5, the camunit 70 comprises: a camshaft 71 rotatably installed to the main body10, and a link arm 73 pivotably installed to the main body 10 and toconnectively move the camshaft 71 so as to rotate the camshaft 71. Thecamshaft 71 is rotatably installed to the base 11, and provided with aplurality of cam projections 71 a. The cam projections 71 a areequi-spaced and contact with the rear surfaces of the friction members50, respectively. If the cam projections 71 a rotate in the direction C,the cam projections 71 a compress and move the friction members 50 inthe second direction B.

[0048] In addition, the camshaft 71 further comprises a link pin 71 b atone end. The link pin 71 b is provided spaced from the rotational centerof the camshaft 71. The rotational axis of the link pin 71 b is parallelto that of the camshaft 71.

[0049] The link arm 73 is pivotably installed to the main frame 13. Oneend of the link arm 73 is formed with a slot 73 a in which the link pin71 b is engaged, and the other end is provided with a guide part 73 b.When the link arm 73 pivots, the link pin 71 b engaged in the slot 73 aconnectively moves the link arm 73, thereby, allowing the camshaft 71 tobe rotated. The guide part 73 b has a contact surface 73 c, which is notparallel to, i.e. slanted in relation to the rotational axle 74 of thelink arm 73. That is, the rotational axle 74 of the link arm 73 isinstalled parallel to a guide shaft 17 to be described later and thecamshaft 71, while the guide part 73 b is formed not to be parallel toeach of the rotational axle 74 and the camshaft 71. As the driving forcesupply unit 80 comes into contact with the guide part 73 while thedriving force supply unit 80 is moving, a driving force is supplied tothe guide part 73 b, whereby, the link arm 73 is made to be rotatable inthe direction D.

[0050] As shown in FIG. 4, the driving force supply unit 80 comprises: acarriage 81 to reciprocate along the guide shaft 17 installed to themain body 10, and a contact member 83 connected to the carriage 81,where the contact member 83 selectively makes contact with andconnectively moves the link arm 73 while moving with the carriage 81.The carriage 81 is reciprocated via a timing belt, which is not shown,when an ink cartridge 15 is received on the carriage. Here, the carriage81 is movable between a predetermined printing area to print an image ona transferred paper, and a home position spaced from the printing areaon either side. That is, the carriage 81 is positioned at the homeposition when the power source of the printing is turned off or during astand-by state. However, during print operation or warm-up, the carriage81 is positioned at the printing area. In the drawing, the home positionis the position where the carriage 81 is confronted with the link arm 73and the printing area is the section to which the arranged frictionmembers 51 face.

[0051] The contact member 83 reciprocates along the guide shaft 17 alongwith the carriage 81, where the contact member 83 is extended towardsthe rear surface of the carriage 83 by a predetermined length. When thecarriage 81 completes the movement from the printing area to the homeposition, the contact member 83 comes into contact with the guide part73 b or the contact surface 73 of the link arm 73 provided to beconfronted with the home position and transfers driving force to thelink arm 73. As a result, the link arm 73 is pushed by the contactmember 83 and pivoted in the direction D. When the carriage 81 ispositioned at the home position, the contact member 83 remains incontact with the guide part 73 b.

[0052] The control section 90 controls the driving of the driving forcesupply unit 80. That is, the control section 90 receives a signal inrelation to a type of paper to be picked up, where the signal istransmitted from the signal generation section 40, and determineswhether the paper is of the first type or the second type of paper. Upondetermining that the paper is of the first type, i.e. a relatively thinpaper is loaded, the control section 90 controls the driving of thecarriage 81, so that the carriage 81 is moved from the printing area tothe home position. As a result, the cam unit 70 connectively moves thefriction members 50 in the second direction B, so that the angle betweenthe leading edge of a paper while being picked, and the friction members50 is reduced. Then, a large frictional resistance is produced at theleading edge of the paper, thereby, preventing concurrent pick up ofmore than one sheet of paper.

[0053] According to an aspect of the present invention, a method to pickup paper using the printing apparatus is described in reference to FIG.6.

[0054] At first, the printing apparatus is warmed up prior to performingthe printing operation. In particular, in a case where the printingapparatus is an ink jet printer, the carriage 81 moves from the homeposition to the printing area, thereby, being in the stand-by position(operation 10). At this time, the carriage 81 is positioned in theprinting area as shown in FIG. 5 and the link arm 73 does not makecontact with the contact member 83. Therefore, as shown in FIG. 7, thefriction members 50 remain offset from the first direction. In thisstate, an information signal in relation to a type of paper to be pickedup is inputted into the control section 90 through the signal supplysection 90 (operation 11). The control section 90 determines whether thepaper to be picked up belongs to the first type of paper or the secondtype of paper based on the inputted information signal.

[0055] Upon determining that the paper belongs to the first type inoperation 12, the control section 90 moves the carriage 81 to the homeposition. Then, as shown in FIG. 8, the contact member 83 moved alongwith the carriage 81 to the home position comes into contact with thecontact surface 73 c of the guide part 73 b and the link arm 73 ispushed and rotated in the direction D by the contact member 83(operation 14). In addition, the camshaft 71 connected to the link arm73 is connectively moved with the link arm 73 and rotated in thedirection C (operation 15). As such, the cam projections 71 a providedon the camshaft 71 forcibly push the rear surfaces of the frictionmembers 50. Accordingly, the friction members 50 are moved in the seconddirection (operation 16). When the friction members 50 are moved in thesecond direction in this manner, the angle formed between the frictionmembers 50 and the leading edge of the paper when the paper is beingpicked up is reduced from the state shown in FIG. 7. As a result, thefrictional resistance applied to the leading edge of the paper by thefriction members 50 increases. In this state, the pick-up unit 30 isdriven and picks up a paper from the paper feeding section 20 (operation17). Then, even when two or more papers tend to be picked up, they areseparated from each other and fed individually because the frictionalresistance of the friction members 50 is large. After a paper is pickedup, the carriage 81 is moved back to the printing area (operation 18).At this time, because the contact between the contact member 83 and thelink arm 75 is released again, the friction members 50 are returned bythe elastic force of the elastic members 60 in the first direction A.And, while the carriage 81 reciprocates in the printing area, an imageis printed as the paper is being picked up and transferred.

[0056] Meanwhile, if a paper to be picked up in operation 12 belongs tothe second type of paper, the friction members 50 is not moved in thesecond direction B. That is, in the case of a thick paper, if thefriction members 50 are moved in the second direction B, the anglebetween the leading edge of the paper and the friction members 50 isreduced and, thus, a large frictional resistance is produced in theleading edge of the paper. In this case, the thick paper may be crumpledwithout being picked up due to the large frictional resistance or thepick-up roller may slide, whereby, the pick-up operation may not beperformed. Therefore, in the case of the second type of paper, the papermay be picked up in the state in which the friction members 50 are laidoffset from the first direction A.

[0057] As described above, according to an aspect of the presentinvention, it is possible to selectively change the position of thefriction members according to a type of paper that is to be picked up.

[0058] Accordingly, when feeding a thick paper, it is possible tosmoothly feed the paper by preventing a large resistance from beingapplied to the leading edge of the paper. Therefore, it is possible tosolve the problem that the paper is crumpled or fails to get picked up.

[0059] In addition, when feeding a thin paper, it is possible to preventtwo or more sheets of paper from being concurrently picked up becausethe structure of the friction members is automatically changed so that alarger resistance is applied to the leading edge of the paper.

[0060] Although a few embodiments of the present invention has beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in this embodiment without departing from theprinciples and the spirit of the invention, the scope of which isdefined in the claims and their equivalents.

What is claimed is:
 1. A printing apparatus having a main body,comprising: a paper feeding section provided to the main body; a signalsupply section to supply a signal indicative of types of paper to be fedfrom the paper feeding section provided to the main body; at least onefriction member provided to form an angle within a predetermined rangein relation to a leading edge of a sheet of paper picked up from thepaper feeding section so that a predetermined frictional force isapplied to the leading edge of the sheet of paper, wherein the structureof the friction member changes within the predetermined range; at leastone elastic member to elastically bias the at least one friction memberin a first direction; a cam unit movably installed to the main body, toforcibly move the at least one friction member in a second directionopposite to the first direction to change the structure of the frictionmember while the cam unit is being moved by driving force; a drivingforce supply unit movably installed to the main body, to supply drivingforce to the cam unit at the time of being moved; and a control sectionto control the driving of the driving force supply unit based on thesignal in relation to the types of paper supplied via the signal supplysection.
 2. The apparatus according to claim 1, wherein the cam unitcomprises: a camshaft rotatably installed to the main body having atleast one projection contacted with the rear surface of the at least onefriction member; and a link arm pivotably installed to the main body andlinked to the camshaft to rotate the camshaft while being pivoted,wherein the link arm is selectively pivoted by the driving force supplyunit.
 3. The apparatus according to claim 1, wherein the driving forcesupply unit comprises: a carriage to receive an ink cartridge, thecarriage installed to the main body so as to reciprocate; and a contactmember connected to the carriage, wherein the contact member makescontact with the cam unit to forcibly move the cam unit to apredetermined area when the carriage moves.
 4. The apparatus accordingto claim 3, wherein the carriage is movable between a printing area toprint an image on the sheet of paper and a home position spaced from theprinting area, and the carriage interferes with the cam unit when thecarriage moves from the printing area to the home position.
 5. Theapparatus according to claim 2, further comprising: the at least onefriction member having two or more friction members with a predeterminedinterval therebetween, at least two cam projections provided to thecamshaft to correspond to the two or more friction members, and a linkpin offset provided at a rotational center of the camshaft.
 6. Theapparatus according to claim 5, wherein the link arm comprises: a slotat one end and a guide part at the other end, wherein the link pin isengaged in the slot and the guide part has a contact surface, which isslantly formed in relation to the direction of the rotational axis ofthe link arm and contacts with the driving force supply unit.
 7. Theapparatus according to claim 1, wherein the signal supply sectioncomprises: a paper detection sensor to detect the type of paper loadedto the paper feeding section.
 8. The apparatus according to claim 1,wherein the signal supply section comprises: a memory to storeinformation regarding the type of paper inputted through a print driver.9. The apparatus according to claim 1, wherein types of the paper loadedto the paper feeding section comprises: a first type of paper having athickness within a predetermined range, and a second type of paperthicker than the first type of paper, wherein when the first type ofpaper is loaded to the paper feeding section, the control section drivesthe driving force supply unit so that the at least one friction memberis moved in the second direction to change the structure of the at leastone friction member.
 10. The apparatus according to claim 9, wherein theat least one friction member forms a larger angle in relation to theleading edge of the sheet of paper to be picked up after being moved toa second position where the at least one friction member has beenforcibly moved than after being moved to a first position where at leastone friction member has been elastically biased.
 11. A method to pick upa paper in a printing apparatus having a main body, at least onefriction member installed to the main body to change structure of thefriction member to form an angle in relation to a leading edge of asheet of paper picked up from a paper feeding unit and elasticallybiased in a first direction; a cam unit movably installed to the mainbody to forcibly move the at least one friction member to a seconddirection while the cam unit is being moved by driving force; and adriving force supply unit movably installed to the main body to supplydriving force to the cam unit at the time of being moved, the methodcomprising: supplying a signal indicative of a type of the sheet ofpaper to be picked up; classifying the paper to a first type having athickness within a predetermined range or a second type thicker than thefirst type of paper based on the signal; supplying a driving force tothe cam unit when the paper is classified as the first type of paper;moving the at least one friction member to the second direction bydriving the cam unit; and picking up the paper from the paper feedingsection when the at least one friction member has been moved in thesecond direction.
 12. The method according to claim 11, wherein theoperation of supplying the signal comprises: supplying a detectionsignal from a detection sensor that detects the type of paper loaded inthe paper feeding section provided to the main body.
 13. The methodaccording to claim 11, wherein the operation of supplying the signalcomprises: supplying a signal from a memory having stored information inrelation to the types of paper inputted through a print driver by auser.
 14. The method according to claim 11, wherein the printingapparatus further comprises a carriage installed in the main body toreciprocate between a printing area and a home position, and a contactmember connected to the carriage to connectively move the cam unit whenthe carriage is moved, wherein the operation of supplying the drivingforce comprises: positioning the carriage at the printing area, movingthe carriage to the home position, and contacting the contact membercomes with the cam unit when the carriage is moved to the home position.15. The method according to claim 11, wherein the printing apparatusfurther comprises a link arm pivotably installed in the main body, andthe cam unit comprises a camshaft provided with at least one camprojection formed to be projected, wherein the operation of moving theat least one friction member in the second direction comprises:contacting the link arm with the driving force supply unit and receivingdriving forceto pivot the link arm, connectively rotating the camshaftlinked to the link arm, and compressing the rear surface of the at leastone friction member in the second direction while the cam projection isbeing rotated along with the camshaft.
 16. The apparatus according toclaim 1, wherein the at least one friction member provided correspondsto the at least one elastic member.
 17. The apparatus according to claim1, wherein an angle formed between the at least one friction member andthe leading edge of the sheet of paper when the at least one frictionmember is moved in the first direction is larger than an angle formedwhen the at least one friction member is moved in the second direction.18. The apparatus according to claim 9, wherein when the second type ofpaper is loaded to the paper feeding section, the control section doesnot drive the driving force supply unit, and the at least frictionmember is not moved in the second direction.
 19. A method to pick up aplurality of papers in a printing apparatus, comprising: classifying theplurality of papers to a first type having a thickness within apredetermined range or a second type thicker than the first type; anddynamically changing a structure of a friction member based on theclassification so that each of the plurality of papers are separatelypicked up.
 20. A method to pick up paper in a printing apparatus,comprising: supplying a signal indicative of types of the paper to bepicked up; classifying the paper to a first type having a thicknesswithin a predetermined range or a second type thicker than the firsttype based on the signal; moving a friction member upon classifying thepaper as the first type or the second type; and picking up the paperwhen the friction member has been moved based on the classification. 21.The method according to claim 20, wherein the operation of supplying thesignal comprises: supplying a detection signal via a detection sensorthat detects the types of paper loaded in the paper feeding sectionprovided to the main body.
 22. The method according to claim 20, whereinthe operation of supplying the signal comprises: supplying a signal froma memory that stores information in relation to the types of paperinputted through a print driver by a user.
 23. The method according toclaim 19, wherein a structure of the friction member allows apredetermined frictional force to be applied to a leading edge of thepaper.
 24. The apparatus according to claim 1, wherein the main bodyfurther comprises: a base; a main frame installed to a top portion ofthe base; and a pivot pin to pivotably connect a lower end of the atleast one friction member to the base of the main body.
 25. Theapparatus according to claim 17, wherein a frictional force between theat least one friction member and the leading edge of the sheet of paperwhen the at least one friction member is moved in the first direction issmaller than when the at least one friction member is moved in thesecond direction.
 26. A method to pick up paper in a printing apparatushaving friction member, comprising: determining whether the paperbelongs to a first type of paper or a second type of paper; moving thefriction member based on the determination, wherein an angle formedbetween the friction member and a leading edge of the paper when thefriction member is moved in a first direction is larger than an angleformed when the friction member is moved in a second direction.
 27. Themethod according to claim 26, wherein a frictional resistance applied tothe leading edge of the paper by the friction member increases when theangle formed between the friction member and the leading edge of thepaper is reduced.
 28. The method according to claim 26, wherein africtional resistance applied to the leading edge of the paper by thefriction member decreases when the angle formed between the frictionmember and the leading edge of the paper is increased.
 29. A printingapparatus having a friction member to pick up paper, comprising: a paperfeeding section to supply a signal indicative of types of paper fed tothe paper feeding section; a friction member to form an angle within apredetermined range in relation to a leading edge of a sheet of paperpicked up from the paper feeding section so that a predeterminedfrictional force is applied to the paper; and a control section tocontrol position of the friction member based on the signal in relationto the type of paper.
 30. The apparatus according to claim 29, furthercomprising: an elastic member to elastically bias the friction member ina first direction; and a cam unit to forcibly move the friction memberin a second direction opposite to the first direction.
 31. The apparatusaccording to claim 30, wherein a frictional force between the frictionmember and the leading edge of the sheet of paper when the frictionmember is moved in the first direction is smaller than when the frictionmember is moved in the second direction.